1. Field of the Invention
This invention relates to modified polystyrene polymers and is more particularly concerned with organo-arsenic derivatives of polystyrene and with processes for their preparation and processes for their use as catalysts for converting isocyanates to carbodiimides.
2. Description of the Prior Art
It is known that certain trihydrocarbyl arsine oxides, of which triphenylarsine oxide is typical, are useful as catalysts for the conversion of organic isocyanates to carbodiimides; see, for example, Monagle, J. Organic Chemistry, 27, 3852, 1962. It has also recently been disclosed (see German Offenlegenschrift 2,504,334 and 2,504,400) that certain phospholane-phosphonic acid salts of amino-modified polymers can be employed as catalysts for the same reaction.
We have now found that certain organo-arsenic derivatives of polystyrene are highly effective catalysts for the conversion of organic isocyanates to the corresponding carbodiimides and are possessed of marked advantages when employed for this purpose.